A Comparative Analysis of Two Different Types of Permanent Magnet Motors with Outer-Rotor Structure for Direct Drive Applications

This paper presents a comparison of the electromagnetic performance between an outer-rotor flux-switching permanent magnet motor (FSPM) and an outer-rotor permanent magnet vernier motor (PMV) for direct drive systems. Both motors employ the same stator and rotor pole pairs, an identical double-layer concentrated winding, and have almost the same volume of PMs and steel laminations. Also, the configuration and main principles are clarified. Then, a comparative analysis of both motors is presented using 2-D finite element analysis (FEA). The results indicate that the PM vernier motor outperforms the FSPM motor in terms of cogging torque. Conversely, the FSPM motor demonstrates superior performance in terms of back electromotive force (EMF), output torque, torque ripple, total loss, and efficiency.